DESCRIPTION: This competing continuation is for a project initially funded in 1985 entitled "Studies of Children's Activity and Nutrition (SCAN)". During the current funding period (4/92-3/96) focus has been upon assessment of the development of hemodynamic mechanisms responsible for blood pressure (BP) control (v cardiac output[CO], total peripheral resistance [TPR]) within the context of ethnicity and family history (FH) early myocardial infarction (MI), defined as having a parent or grandparent with an MI at less than 55 years of age (FH+). Blacks have a higher mortality rate through middle adulthood than whites from coronary heart disease(CHD), the leading causes of death in the United States. Blacks have been found to exhibit greater cardiovascular (CV) response to stress (i.e., reactivity), a potential risk factor for CHD, as have FH+ individuals. Although CHD has its pathobiologic origins in childhood, little longitudinal reactivity research has been conducted in youth, especially from childhood through late adolescence. This is particularly the case with regard to lack of evaluation of: 1) the hemodynamic mechanisms responsible for BP control (i.E, CO, TPR), 2) stability of FH and/or ethnicity reactivity differences across this time period, 3) inclusion of moderator variables which may account for or accentuate FH and ethnicity reactivity differences and most importantly, 4) the predictive relationships between reactivity and pathobiologic markers of CHD risk (i.e., increased resting BP, left ventricular mass and degree of concentric remodeling and decreased carotid artery wall elasticity and endothelium dependent arterial dilation [EDAD]). This application will address these deficiencies by following a multiethnic sample of 250 13 to 14 year olds for an additional 5 years to determine: 1) whether BP reactivity during childhood predicts changes in resting BP, left ventricular mass and concentric remodeling, carotid artery wall elasticity and EDAD up to 11 years later after controlling for other expected predictors (i.e., age, gender, ethnicity, resting BP, adiposity, ambulatory BP); 2) the influence of ethnicity, FH and a select group of moderator variables (i.e., environmental stress, anger and John Henryism coping styles, aerobic fitness on youth's CV reactivity; and 3) the stability of CV reactivity and a 24- hour ambulatory BP from childhood through late adolescence. The long- term objectives are to provide a better understanding of the development of CV reactivity in youth and its influence upon early pathobiologic markers of CHD prior to overt manifestation of disease. This information may eventually be used to identify youth who are at greatest risk for development of CHD and foster the development of interventions that may prevent early CHD onset and improve health.